International Journal of Oral Implantology, 03/2019

Purpose: To compare the clinical outcome of fixed prostheses supported by 4- to 8-mm-long implants with prostheses supported by longer implants placed in vertically augmented atrophic mandibles after a follow-up of 5 years in function. Materials and methods: The Cochrane Central Register of Controlled Trials (CENTRAL) and MEDLINE were searched up to 1st September 2018 for randomised controlled trials (RCTs) with a follow-up of at least 5 years in function comparing fixed prostheses supported by 4- to 8-mm-long implants with prostheses supported by longer implants placed in vertically augmented atrophic mandibles. Outcome measures were prosthesis failure, implant failures, augmentation procedure failures, complications, and peri-implant marginal bone level changes. Screening of eligible studies, assessment of the risk of bias and data extraction were conducted in duplicate and independently by two review authors. The statistical unit of the analysis was the prosthesis. Results were expressed as random-effects models using mean differences for continuous outcomes and risk ratios (RR) for dichotomous outcomes with 95% confidence intervals (CIs). Results: Four eligible RCTs that included originally 135 patients were included. Two RCTs had a parallel-group design and two a split-mouth design. Short implants were 5.0 to 6.6 mm long and were compared with longer implants placed in posterior mandibles augmented with interpositional blocks of bone substitutes. All trials were judged at unclear risk of bias. Twelve (14%) bone augmentation procedures failed to achieve the planned bone height to allow placement of implants with the planned length. Five years after loading, 28 patients (21%) had dropped out from the four RCTs. There were no differences for patients having prosthesis (RR = 1.46; 95% CI: 0.52 to 4.09; P = 0.47; I2 = 0%) or implant (RR = 1.00; 95% CI: 0.31 to 3.21; P = 1.00; I2 = 0%) failures between the two interventions, but there were more patients experiencing complications (RR = 4.72; 95% CI: 2.43 to 9.17; P < 0.00001; I2 = 0%) and peri-implant marginal bone loss (mean difference = 0.60 mm; 95% CI: 0.36 to 0.83; P < 0.00001; I2 = 45%) at longer implants in augmented bone. Conclusions: Five years after loading, prosthetic and implant failures were similar between the two interventions, but complications and peri-implant marginal bone loss were higher and more severe at longer implants placed in vertically augmented mandibles. Larger trials and longer follow-ups up to 10 years after loading are needed to confirm or reject the present preliminary findings. However in the meantime short implants could be the preferable option. Keywords: dental implants, randomised controlled trial, short implants, systematic review, vertical augmentation review Conflict of interest statement: Several authors of this review were also authors of the included original trials; however, risk of bias assessment was done in duplicate by two authors not involved in the conduction of the original trials. This review was self-funded.

Purpose: To assess the failure rate of dental implants and prosthetic restoration, complications and marginal bone loss (MBL) of implants restored with an immediate definitive abutment at the time of the implant placement, and implants that were evaluated according to a standard prosthetic protocol (SPP), which includes multiple abutment changes. Materials and methods: This systematic review followed the guidelines of the PRISMA statement (Preferred Reporting Items for Systematic Reviews and Meta-Analyses). An electronic search with no date or language restriction was run in January 2018 in the PubMed/MEDLINE, Cochrane Central Register of Controlled Trials, Web of Science, and complemented with a manual search. Randomised clinical trials with at least a 12-month follow-up evaluating the use of a definitive abutment and a SPP were included. The Cochrane Collaboration Risk of Bias tool was used to evaluate the included studies. The outcome measures were: implant and prosthetic failure; aesthetics; complications; and peri-implant MBL. The results were pooled using a random-effect model with mean differences (MDs) for continuous outcomes and risk ratio for dichotomous outcomes with a 95% confidence interval (CI). Results: The search identified a total of 714 studies. After the screening process five studies were included in the analysis. The five studies included had a limited sample size, a short follow-up period, and four studies were considered at high risk of bias. The meta-analysis revealed that five studies using an immediate definitive abutment over a 12- to 18-month follow-up resulted in lower MBL, with a MD of -0.32 mm (95% CI -0.45 to -0.19: P 0.0000). At the end of a 3-year follow-up two studies showed a MD of -0.33 mm (95% CI -0.63 to -0.03: P = 0.03, which also favours the definitive abutment group. Regarding implant failure rate, complications, and probing depth, no significant difference was found between the groups. Conclusions: Within the limitations of this meta-analysis, reducing the number of abutment changes contributes to statistically significant lower MBL. However, the clinical significance of this reduction in bone loss should be interpreted with caution. A high implant success rate was reported by all studies for both control and test groups. Keywords: alveolar bone loss, dental implants, implant restoration, review Conflict of interest statement: The authors declare that they have no conflicts of interest. No funding was received for this review.

Purpose: To report the 5-year outcomes of autogenous bone block grafts fixed at a distance (BBG-D) versus a resorbable poly-D-L-lactide foil fixed at a distance (SonicWeld Rx shell technique [SWST]) randomised controlled trial, for lateral alveolar ridge augmentation. Materials and methods: Thirty patients with a buccopalatal bone width of ≤ 3 mm were randomised into the following treatment groups: BBG-D and SWST. The implant survival, changes in bone morphology visualised in a cone beam computed tomography scan and periodontal parameters were assessed. Results: Thirteen patients in the BBG-D group and seven in the SWST group could be included in the analysis. All implants that osseointegrated initially (BBG-D = 13 and SWST = 7) were functional at the 5-year re-evaluation. The buccopalatal bone width significantly (P 0.001) decreased over time regardless of the study group. A bone loss of 0.00 mm was observed at the distal implant shoulder in the BBG-D group and 0.29 mm (SD 0.49 mm) in the SWST group (P = 0.04). The mean buccal bone loss was 2.56 mm (SD 3.65 mm) in the BBG-D group and 1.71 mm (SD 4.11 mm) in the SWST group (P = 0.64). The mean probing pocket depth was within sound limits in both groups without significant differences (P > 0.05). Bleeding on probing was low. Conclusions: Within the limitations of this study, a similar implant survival rate was observed between the BBG-D and SWST techniques during the 5-year follow-up. The buccopalatal bone width decreased over time regardless of the augmentation method used. Keywords: bone graft, buccal bone, cone beam computed tomography (CBCT), dental implant, poly-D-L-lactide (PDLLA) foil Conflict of interest statement: The study was not funded. The authors declare no conflicts of interest.

Purpose: To assess the clinical performance of single crowns in the posterior maxilla supported by either 11-mm-long implants combined with maxillary sinus floor elevation surgery or 6-mm-long implants during a 5-year follow-up period. Materials and methods: A total of 38 consecutive patients, missing a premolar or a molar in the posterior maxilla and residual bone height underneath the maxillary sinus between 6 to 8 mm, were included. Subjects were randomly allocated to receive one 11-mm-long implant in combination with maxillary sinus floor augmentation or to receive one 6-mm-long implant without any grafting. A total of 41 implants (21 implants in 20 patients in the 6-mm group, and 20 implants in 18 patients in the 11-mm group) were placed and subsequently restored after 3 months with custom-made titanium abutments and cemented zirconia-based porcelain crowns. Both groups were followed by clinical (implant survival, restoration survival, complications, pocket probing depth and presence of plaque, calculus, bleeding and peri-implant inflammation) and radiographic examinations up to 5 years. The patient satisfaction was scored before treatment, and 12 and 60 months after functional implant restoration. Results: One patient (11-mm group) died before the 12-month evaluation and one patient (6-mm group) moved away. In addition, one patient in the 6-mm group lost one implant and no implants were lost in the 11-mm group. Two patients lost three restorations in the 6-mm group and no restorations were lost in the 11-mm group. From loading until the 60-month assessment, the mean marginal bone loss in the 6-mm group and the 11-mm group was 0.12 ± 0.36 mm and 0.14 ± 0.63 mm, respectively, without a significant difference (mean difference 0.02 mm; 95% CI -0.32 to 0.37; P = 0.884). Implant loss, restoration loss, screw loosening and porcelain chipping were defined as complications. Four patients in the 6-mm group and one patient in the 11-mm group had one or more complications, without a significant difference between the groups (95% CI 0.019 to 0.244; P = 0.198). The patient satisfaction was high in both groups (mean overall satisfaction in the 6-mm and the 11-mm groups was 9.4 ± 0.8 and 9.2 ± 0.8, respectively; mean difference 0.2; 95% CI -0.33 to 0.76; P = 0.434). Conclusions: Reconstructions performed using an 11-mm implant combined with maxillary sinus floor augmentation or a 6-mm implant in the resorbed posterior maxilla are equally successful in supporting a single restoration over 5 years. Keywords: posterior maxilla, randomised controlled trial, short dental implants, single crowns Conflict of interest statement: This two-centre study has been partially sponsored by Dentsply Implants. None of the authors has an economic interest in the products related to this study or in the company.

Purpose: To investigate whether functional factors estimated by the masseter muscle thickness (MMT) and the maximum occlusal force (MOF), were associated with the amount of continuous eruption of maxillary incisors in adults. Materials and methods: Dental casts were taken twice in 24 adult female patients during a 10-year prospective cohort study. At the first appointment, ultrasonographic measures of the MMT and MOF were recorded. The casts were scanned into a digital model and measurements of the eruption and clinical crown lengthening (CL) of the maxillary incisors were calculated after superimpositions on the palatal region. Univariate and multivariate mixed effect regression models were used to assess the single and joint role of functional factors, with presence or absence of occlusal contacts and CL on incisor eruption. Results: By using the linear mixed effects regression model, we observed that both the MMT and MOF were correlated with the maxillary incisor eruption. In particular, the thicker the masseter or the stronger the occlusal force, the lower the amount of eruption. Using a backward multivariable mixed effects model, the incisor eruption was correlated with the MMT combined with presence or absence of contacts and clinical CL. The amount of tooth eruption (0.32 mm on average) was positively associated with CL (0.29 mm on average); therefore, the greater the CL (gingival recession), the greater the amount of tooth eruption. The presence of occlusion contact between the maxillary incisors and their mandibular antagonists was found as an inhibitor of eruption in the multivariate model. Conclusions: The functional capacity of masticatory muscles, as estimated by the MMT, plays a role in the amount of maxillary incisor eruption. The stronger the masticatory muscles, the lower the amount of eruption. Keywords: aesthetics, continuous eruption, diagnostic procedure, implant stability, maximum occlusal force, STROBE guidelines Conflict of interest statement: All the authors declare that they have no conflict of interest.

Purpose: Osteotome sinus floor elevation (OSFE) is a technique aimed at simplifying implant placement in the posterior atrophic maxilla. The necessity of bone grafting under the elevated sinus membrane has been widely debated. The aim was to compare the evolution over 5 years of implant stability in sites grafted or left ungrafted. Materials and methods: A total of 12 patients (9 female and 3 male) presenting ≤ 4 mm initial bone height (IBH) in the posterior maxillary sites were recruited. Implants (n = 37) were placed using OSFE. According to the randomisation, the sinuses received either bone graft (n = 20, control group) or no graft (n = 17, test group). Patients received both these treatments when both sinuses fulfilled the inclusion criteria. Control assessments were performed 1 week, 10 weeks, 12 weeks, and then 1 year, 3 years and 5 years after the implant placement. Periapical radiographs were taken and the implant stability quotient (ISQ) was measured at different time points. Results: At implant surgery, the mean ISQ was 58.9 ± 11.2 for the test group and 53.8 ± 10.2 for the control group; it plummeted 10 weeks after the implant placement and rose thereafter. Five years after the implant placement, the mean ISQ reached 80.8 ± 4.2 for the control group, and 79.7 ± 4.3 for the test group. The difference between the groups was not significant. The IBH significantly affected implant stability at implant insertion and 5 years after the implant insertion, but not at the other time points. Conclusions: The implants performed using OSFE in ungrafted sites were as stable as the implants placed in grafted sites. Keywords: bone graft, implant stability quotient (ISQ), osteotome sinus floor elevation (OSFE), posterior maxilla, resonance frequency analysis (RFA) Conflict of interest statement: All authors report no conflict of interest.

Purpose: This report originated from the finding of metal artefacts on magnetic resonance images (MRI) which were not detected on panoramic radiography or cone beam computed tomography (CBCT) imaging. It was hypothesised that drills or implants might release metal particles during surgical procedures in the jawbones. Therefore, the aim was to assess whether dental implants or surgical drills might cause metal debris in the surrounding tissues. Materials and methods: The experiment consisted of a postmortem and an antemortem model. A split-mouth design was carried out in a postmortem fresh frozen cadaver head. In the left mandible only the drill preparation sequence was performed, whereas in the right mandible, the drill sequence was followed by implant placement. Before surgery, the postmortem model underwent a baseline MRI acquisition. A second MRI (MRI2) was acquired after performing the osteotomies on both sides and implant placement on the right side. Finally, the implants were carefully removed, and a final MRI (MRI3) was acquired. Bone blocks containing the implant and osteotomy sites were isolated. For the antemortem model, a fresh frozen cadaver head was selected that already had implants in place. An implant in the anterior maxilla was removed and the surrounding bone block was isolated as well. A histological analysis was prepared for both models. Results: In the antemortem model, histological analysis showed irregular-shaped dark particles near the bone-implant interface consistent with metal debris. Additionally, in the postmortem model, both sites showed metal artefacts on MRI2 and MRI3, and by using a balanced fast field echo sequence, and histological analysis, the suspected particles of metal debris were confirmed on both sides of the mandible. Conclusions: Further studies should investigate the origin and extent of the metal debris following implant placement, as well as its clinical significance, possible risk factors and preventive measures. Keywords: artefacts, dental materials, magnetic resonance imaging, radiology Conflict of interest statement: The authors declare no financial disclosures or conflicts of interest.

Purpose: To illustrate the workflow for simultaneous LeFort I maxillary advancement and zygomatic implant (ZI) placement. Materials and methods: Three consecutive patients referred for the rehabilitation of the severely atrophic maxilla were treated with simultaneous LeFort I maxillary advancement and ZI placement. An evaluation of the treatment protocol was carried out to validate the proposed workflow: indications, treatment planning, surgical splint manufacturing, surgical procedure and prosthetic loading. Results: Maxillary reposition was carried out according to the previous virtual planning. Consequently, in all cases extrasinusal or sinus slot paths were used, proper emergence of the implant platform fully surrounded by alveolar bone was ensured, and full-arch rehabilitation supported by ZI was performed. A straight facial profile was achieved postoperatively in all cases and no surgical complications were noted. No resorption of maxillary distal bone was evident at the end of the first year of follow-up. However, a mean relapse of −4.3 mm (−10.06%) was evidenced for maxillary downward movement, and conversely, an extra-forward maxillary movement was observed (mean +1.4 mm, +82.8%) in all cases. Conclusions: Besides restoring oral function and aesthetics, this technique avoids donor site morbidity, decreases surgical time, and shortens the overall rehabilitation period. Keywords: bone resorption, edentulous patient, maxillary advancement, maxillary atrophy, zygomatic implant placement Conflict of interest statement: The authors have no financial interests to declare regarding the contents of this article.